Distributed Acoustic Sensing (DAS) is a technology whereby a fibre optic cable is transformed into tens of thousands of seismic sensors, that recently has seen rapid uptake by the oil and gas sector as a monitoring technology. The advantages of DAS include the lost-cost of fibre optic cables and its ability provide high resolution datasets spanning 10’s of km on the ground or the full length a the well. Many applications of DAS datasets in O&G utilise a fibre deployed down-hole and are for the purpose of geophysical surveys such as VSP or passive seismic monitoring. However, it is also possible to use DAS responses to investigate of fluid flow in the well or the reservoirs slow-strain response to stimuli. As such DAS acquisition is also applicable in settings such as CO2 sequestration and geothermal projects. In fact, the ubiquity of fibre optic cables throughout our society extends the potential uses for DAS beyond those directly related to the subsurface into areas such as; seismic monitoring, leak detection, railway and road traffic monitoring, security and intruder detection, as well as infrastructure monitoring.
Here I will outline some of the basic principles and applications of DAS surveys as well as describing some of the challenges int DAS acquisition. In particular, DAS surveys are limited by the very high data rates produced the acquisition hardware (up to 10's of TB/day). These large data volumes make DAS data difficult to analyse and cumbersome to extract from the field location. To address this issue Motion Signal Technologies has developed the Compression At The Edge (CATE) acquisition system. CATE is capable of compressing DAS data as it is acquired in real time, such that the data can be archived locally and or transmitted from field using a band limited connection. The system has been tested in a variety of settings and the results include recordings from fibre optic cables positioned beside train lines in the UK, which in addition to monitoring railway security and condition show clear signals from the Feb 6th Turkey Earthquake. I will also present results from a trial using (possibly the first) temporary downhole fibre deployed in a geothermal well to record a VSP/ Check shot survey. The results show clear detections of the first arrivals beyond 3.5km depth and provide an important constraint on the velocity model used to locate natural and induced seismic events in the area.
Distributed Acoustic Sensing (DAS) is a technology whereby a fibre optic cable is transformed into tens of thousands of seismic sensors, that recently has seen rapid uptake by the oil and gas sector as a monitoring technology. The advantages of DAS include the lost-cost of fibre optic cables and its ability provide high resolution datasets spanning 10’s of km on the ground or the full length a the well. Many applications of DAS datasets in O&G utilise a fibre deployed down-hole and are for the purpose of geophysical surveys such as VSP or passive seismic monitoring. However, it is also possible to use DAS responses to investigate of fluid flow in the well or the reservoirs slow-strain response to stimuli. As such DAS acquisition is also applicable in settings such as CO2 sequestration and geothermal projects. In fact, the ubiquity of fibre optic cables throughout our society extends the potential uses for DAS beyond those directly related to the subsurface into areas such as; seismic monitoring, leak detection, railway and road traffic monitoring, security and intruder detection, as well as infrastructure monitoring.
Here I will outline some of the basic principles and applications of DAS surveys as well as describing some of the challenges int DAS acquisition. In particular, DAS surveys are limited by the very high data rates produced the acquisition hardware (up to 10's of TB/day). These large data volumes make DAS data difficult to analyse and cumbersome to extract from the field location. To address this issue Motion Signal Technologies has developed the Compression At The Edge (CATE) acquisition system. CATE is capable of compressing DAS data as it is acquired in real time, such that the data can be archived locally and or transmitted from field using a band limited connection. The system has been tested in a variety of settings and the results include recordings from fibre optic cables positioned beside train lines in the UK, which in addition to monitoring railway security and condition show clear signals from the Feb 6th Turkey Earthquake. I will also present results from a trial using (possibly the first) temporary downhole fibre deployed in a geothermal well to record a VSP/ Check shot survey. The results show clear detections of the first arrivals beyond 3.5km depth and provide an important constraint on the velocity model used to locate natural and induced seismic events in the area.